Flashcards in MTB - Infectious Disease Deck (230):
Main body areas affected by staph.aureus infection
bone, heart, skin, joint
DOC: sensitive staph. aureus (MSSA)
IV: oxacillin/nafcillin or cefazolin (first gen ceph)
oral: dicloxacillin or cephalexin (first gen ceph)
DOC: MRSA - severe infection
vancomycin, linezolin, daptomycin, ceftaroline, tigecycline or telavancin
vancomycin derivative w/ similar efficacy
DOC: minor MRSA infection
TMP-SMX, clindamycin, doxycycline
penicillin allergy (tx of staph aureus)
rash - cephalosporins safe
anaphylaxis - macrolides or clindamycin
if severe infection --> vancomycin, linezolid, daptomycin, telavancin
which antibiotics are specific for streptococcus?
which drug class works synergistically with other agents to tx. staph and strep?
which drugs are excellent anti-anaerobic medications?
- also cover all strep and all MSSA
broad action against gram negative bacilli
which drugs are excellent pneumococcal drugs?
levofloxacin, gemifloxacin, moxifloxacin
cover gram negative rods, streptococci and anaerobes
Only carbapenem that does not cover pseudomonas
DOC: abdominal anaerobes
only cephalosporins that cover anaerobes
which other drug classes have equal efficiacy to metronidazole for abdominal anaerobes
DOC: respiratory anaerobes (resp strep)
medications with NO anaerobic coverage
red man syndrome --> red, flushed skin from histamine release due to rapid infusion rates. If this happens - slow the infusion rate down (no need to switch medications)
Tx. herpes simplex, varicella zoster
acyclovir, valacyclovir, famciclovir
- all are equal in efficacy
valganciclovir, ganciclovir, foscarnet
- equal in efficacy
- also cover HSV and VZV
best long term therapy for CMV retinitis
s/e: valganciclovir and ganciclovir
bone marrow suppresion, neutropenia
tx. infuenza A and B
oseltamavir and zanamavir (neuraminidase inhibitors)
Tx. Hepatitis C and RSV
Fluconazole - what does it cover?
candida (oral and vaginal), cryptococcus
same as fluconazole but harder to use therefore, rarely initial therapy for anything
what drug covers all the candida species?
best agent against aspergillus?
caspofungin, micafungin, anidulafungin
What are the echinocandins useful for?
neutropenic fever patients (less mortality than amphotericin) but do NOT cover cryptococcus
none - affect/inhibit 1,3 glucan synthesis which does not exist in humans
what drug is effective against all candida, cryptococcus and aspergillus?
- but basically there is a drug from above classes that is better or equal to with less side effects
fever, shakes, chills
best initial test in suspected osteomyelitis?
(although may take up to 2 weeks before changes are seen)
best 2nd line test of osteomyelitis (i.e. negative XR but high clinical suspicion)
most accurate test for osteomyelitis?
bone biopsy and culture
earliest finding of osteomyelitis in XR
elevation of periosteum
best method for following response to therapy in osteomyelitis
- if still elevated after 4-6 weeks of therapy, further treatment or surgical debridement may be necessary
MCC of osteomyelitis
continguous spread from overlying tissue
which test is more superior in osteomyelitis - MRI vs. bone scan?
- they have equal sensitivity but MRI is far more specific
in osteomyelitis, is culturing the sinus tract or ulcer beneficial?
no - you should not do this
if sensitive: IV oxacillin or nafcillin for 4-6 weeks
if MRSA: vanco, linezolid or daptomycin
--> ORAL therapy is never appropriate
what must be done prior to initiating treatment for osteomyelitis?
- no urgency in treating chronic osteomyelitis; obtain biospy, move clock forward and tx. what you find on culture
which type of osteomyelitis can be treated with oral drugs?
pseudomonas or salmonella osteomyelitis
patient comes in with itching and drainage from the external auditory canal; on physical exam, his ear is painful to manipulation - likely dx?
Dx. otitis externa
physical exam - no culture
Tx. otitis externa
1. topical antibiotics - ofloxacin or polymyxin/neomycin
2. add topical hydrocortisone (helps swelling/itching)
3. add acetic acid/water solution to reacidify
malignant otitis externa
osteomyelitis of the skull caused by pseudomonas in a patient with diabetes
dx. malignant otitis externa
tx. like osteomyelitis (XR, MRI, bone biopsy/culture)
tx. malignant otitis externa
antibiotics -> cipro, piperacillin, cefipime, carbapenem, aztreonam
most sensitive finding of otitis media
immobility of tympanic membrane
CF: otitis media
absent light reflex
decreased mobility of TM
best initial therapy otitis media
amoxicillin, 7-10 days
recurrent or persistent otitis media - management?
tympanocentesis and aspirate of TM for culture
CCS otitis media
advance clock 3 days - if infection not improving, switch amoxicillin to: amoxi-clav, cefdinir, ceftibuten, cefuroxime, cefprozil, cefpodoxime
best initial test: sinusitis
most accurate test: sinusitis
sinus aspirate for culture
when should you use antibiotics to treat sinusitis?
- fever and pain
- persistent sx. despite 7d of decongestants
- purulent nasal d/c
organisms that cause sinusitis (and otitis media)
first sx --> decongestants
second --> amoxicillin + inhaled steroids
best initial test: pharyngitis
rapid strep test
tx. pharyngitis is allergic to penicillin
azithromycin or clarithromycin
next best step in patient that has influenza symptoms
viral antigen detection of nasopharyngeal swab
oseltamavir or zanamavir - if pt presents w/in 48 hr onset of symptoms. If not - symptomatic therapy
Impetigo - organisms
strep pyogenes or staph aureus
what is impetigo?
superficial bacterial skin infection (epidermal layer)
weeping,"honey" crusting and oozing of the skin
topical mupirocin or retapamulin
severe? oral dicloxacillin or cephalexin
community acquired MRSA impetigo
group A (pyogenes) strep infection; MC location - face
Dx. testing in erysipelas
order blood cultures on CCS but single best answer: start treatment
best initial therapy: erysipelas
oral dicloxacillin or cephalexin
- if confirmed group A strep: penicillin VK
can erysipelas lead to rheumatic fever?
no - only glomerulonephritis
if there is cellulitis of the leg - what should you order?
LE Doppler to exclude a blood clot
MCC of cellulitis
staphylococcus aureus and streptococcus pyogenes
Tx. cellulitis (minor dz)
PO - dicloxacillin or cephalexin
Tx. cellulitis (severe dz)
oxacillin, nafcillin or cefazolin IV
T/F: does staph epidermidis cause skin infections - if true, which one?
false - normal skin flora
staph infection of hair follicle
increasing in size: furuncle < carbuncle < boil < abscess
same as for cellulitis
PO - dicloxacillin or cephalexin
IV - oxacillin, nafcillin or cefazolin
best initial test for fungal infection of the skin
Tx. fungal skin infection (no hair or nail involvement)
clotrimazole, miconazole, ketoconazole, nystatin, ciclopirox etc
Tx. fungal skin infection involving hair (scalp) or nails
PO anti-fungals --> terbenafine, itraconazole or griseofulvin
urethral discharge is always a sign of....
+/- dysuric symptoms
Dx. testing urethritis
urethral swab - gram stain, WBC, culture, DNA probe
two drugs - need to target gonorrhea and chlamydia
1. Ceftriaxon IM or PO Cefpodoxime
2. Azithromycin (single dose) or doxycycline 7d
patient is presenting with recurrent episodes of gonorrhea - what should they be tested for?
terminal complement deficiency
CF: disseminated gonorrhea
1. petechial skin rash
2. polyarticular disease
single best test for both gonorrhea or chlamydia
- blind swab for NAAT is just as accurate as speculum examination
exactly same as urethritis - cover for gonorrhea and chlamydia
1. Ceftriaxon IM or PO Cefpodoxime
2. Azithromycin (single dose) or doxycycline 7d
Pt presents with lower abdominal pain, tenderness, fever, dysuria, discharge and cervical motion tenderness - you suspect?
pelvic inflammatory disease
in PID - what test is a measure of severity of the disease?
WBC count - leukocytosis
best initial test in suspected PID
pregnancy test --> cervical culture --> DNA probe
most accurate test for dx of PID
laparoscopy --> only done for recurrent or persistent infection despite therapy
what kind of specimens can you use for NAAT?
men - urine
women - blind vaginal swab
Outpatient Tx. PID
Inpatient Tx. PID
IV Cefoxitin or Cefotetan
What abx are safe in pregnancy?
Male pt presents with painful and tender testicle w/ normal position of testicle in scrotum - dx?
< 35: Ceftriaxone + Doxy
> 35: FQs
best initial test for chancroid
swab for gram stain (gram neg.) and culture (medium: Nairobi or Mueller-Hinton medium)
single dose of either: IM Ceftriaxone or PO Azithromycin
CF: lymphogranuloma venereum
genital ulcer + large, tender LN that may develop suppurating, draining sinus tracts
Dx. lymphogranuloma venereum
serology for Chlamydia trachomatis
Tx. lymphogranuloma venereum
Doxycycline or Azithromycin
clear vesicular lesions on genitals - dx?
Herpes simplex virus
Next best step in management in pt who presents with multiple, clear vesicular lesions on genitals
Antivirals for 7-10d
(acyclovir, valacyclovir or famciclovir)
which anti-viral is safe to use in pregnancy?
- use in pregnancy if evidence of active lesions at 36 weeks
when would you do a Tzanck prep?
If patient has multiple vesicular genital lesions that have become ulcers
most accurate test for herpes
acyclovir resistant herpes is treated with...
most accurate test in primary syphillis
initial diagnostic test in primary syphillis
darkfield then VDRL/RPR
Tx. primary syphillis
single IM dose of penicillin
penicillin allergy? doxycycline
patients being treated for primary syphillis may develop fever, headache and myalgia 24 hours after starting treatment; it is self-limiting; tx. w/ aspirin
CF: secondary syphillis
initial dx. test in secondary syphillis
RPR and FTA
Tx. secondary syphyllis
single IM dose of penicillin
doxy for pen-allergic pts
when do you do desensitization for tx. of a syphillis patient?
initial dx. test in tertiary syphillis
RPR or FTA
LP for neurosyphilis
Tx. tertiary syphilis
desensitize if pen-allergic
which test is more sensitive for neurosyphillis?
FTA > VDRL
cause: Klebsiella granulomatis
beefy red genital lesion that ulcerates
dx. granuloma inguinale
biopsy or touch prep
tx. granuloma inguinale
doxycycline, TMP/SMX or azithromycin
best initial test for cystitis
most accurate test for cystitis
Tx. uncomplicated cystitis
PO TMP/SMX 3d; if E.coli resistance 20% - Cipro or Levofloxacin
Tx. complicated cystitis
7d TMP/SMX or Ciprofloxacin
what is complicated cystitis?
means there is an anatomic abnormality such as a stone, stricture, tumor or obstruction
who should get an USG if they have cystitis?
Men - it is unusual for a male patient to have a UTI in absence of anatomic abnormality
does everyone need a urine culture if you suspect cystitis?
No - clear symptoms + leukocytes on U/A --> go straight to treatment for 3d
Tx. outpatient pyelonephritis
Tx. inpatient pyelonephritis
ampicillin / gentamicin
nitrites on U/A are indicative of...
gram negative infection
a patient with diagnosed pyelonephritis is not responding to tx. with antibiotics after 7 days - what should you be considering?
Initial test in suspected pyelonephric abscess
CT scan or USG
Tx. pyelonephric abscess
quinolone and staph coverage (oxacillin/nafcillin)
prostatitis - best initial test
prostatitis - most accurate test
WBCs on U/A after prostate massage
ciprofloxacin - extended period of time
how many Duke's criteria do you need to dx. infectious endocarditis?
1 major + 3 minor
Duke's Major Criteria (2)
1. Two positive blood cultures
2. Abnormal echo
Duke's Minor Criteria (5)
1. Fever > 38.5
2. Presence of RFs: IVDA, structural heart dz, prosthetic valves, dental procedures, positive history
3. vascular findings
4. immunologic findings
5. positive blood culture
Next best step in patient with fever + new or changing heart murmur
- if positive --> do an ECHO
best empiric therapy - infective endocarditis
Vancomycin + Gentamicin for 4-6 weeks
patient with infective endocarditis, blood cultures grow S. bovis - what test should be done?
- S.bovis is assoc. w/ colonic pathology
When do you consider valve replacement as a tx. for infective endocarditis?
1. anatomic defects
- valve rupture
- prosthetic valves
2. fungal infections
3. embolic events ones started on abx
which cardiac defects need endocarditis prophylaxis?
1. prosthetic valves
2. unrepaired cyanotic heart dz
3. previous endocarditis
4. transplant recipients who develop valve dz
which procedures need endocarditis prophylaxis?
1. dental procedures that cause bleeding
2. respiratory tract surgery
3. surgery of infected skin
DOC: endocarditis prophylaxis
when should you start HAART therapy?
1. CDC < 500
2. symptomatic regardless of CDC
4. needle stick scenario w/ HIV positive patient
S/E: protease inhibitors
post-exposure prophylaxis (HIV)
i.e. needlestick, mucosal exposure or unprotected sex
Tx. HAART for one month
when do you start prophylaxis for PCP in HIV + and what do you use?
CDC < 200
- use atovaquone or dapsone if rash develops
MAC prophylaxis in HIV +
CDC < 50
Tx. PO azithromycin, once weekly
what opportunistic infection presents w/ SOB, dry cough, hypoxia and increased LDH?
best initial test for PCP?
CXR (increased interstitial markings)
most accurate test for PCP?
best initial tx. for PCP?
if rash - use IV pentamidine
mild cases? IV atovaquone
Tx. severe PCP (pO2 < 70 and A-a gradient > 35)
IV TMP/SMX plus steroids
HIV+ pt presents with headache, nausea, vomiting and focal neuro findings - you suspect...and order what test first?
best initial test - head CT w/ contrast
pyrimethamine and sulfadiazine for 2 weeks
repeat head CT - if lesions smaller confirmation of toxo; if unchanged - biopsy needed
HIV pt with a CDC < 50 presents with blurry vision - what are you concerned about? best initial test?
- performed dilated ophtho examination
Tx. CMV retinitis
ganciclovir or foscarnet
maintenance therapy w/ valganciclovir is lifelong
HIV pt with CDC < 50 presents with fever and headache - which diagnostic test should you do? best initial vs. most accurate?
Lumbar puncture - increased lymphocytes
best initial = india ink stain
most accurate = cryptococcus antigen test
Tx. cryptococcus in HIV pt
Amphotericin followed by lifelong fluconazole
Patient with exposure to food and animal urine presents with fever, abdominal pain and muscles aches. He has jaundice. Dx?
ceftriaxone or penicillin
A rabbit hunter presents to you with enlarged LNs, conjunctivitis and a large ulcer on his hand. Dx?
Dx test and Tx. of tularemia
Tx. bentamicin or streptomycin
Management in patient with characteristic erythema migrans rash
Tx. with doxycycline w/o further testing
MC late manifestation of Lyme dz
MC cardiac manifestation of Lyme dz
AV conduction block/defect
MC neurologic manifestation of Lyme dz
7th CN palsy
Tx, rash, joint dz or Bell's palsy as a complication of Lyme dz
PO doxycycline or amoxicillin
Tx. CNS or cardiac involvement as a result of Lyme dz
Patient presents to you after a camping trip with hemolytic anemia - dz?
1. peripheral blood smear
- tetrads of intraerythrocytic ring forms
azithromycin and atovaquone
Patient comes back from a camping trip with elevated LFTs, thrombocytopenia and leukopenia - dz?
peripheral blood smear
- morulae (inclusion bodies in WBCs)
Tx. acute malaria
quinine + doxycycline
Prophylaxis for malaria
1. Weekly Mefloquine
2. Daily Atovaquone/Proguanil
branching gram positive filaments that are weakly acid fast
best initial test / most accurate test - Nocardia
best initial = CXR
most accurate = culture
gram positive branching, filamentous bacteria that growns on anaerobic culture
- look for pt w/ history of dental or facial trauma
Patient who was just bat cave exploring in Ohio presents with a viral-like syndrome along with oral ulcers and splenomegaly - dx?
best initial test - histoplasmosis
urine antigen test
most accurate test - histoplasmosis
biopsy + culture
acute pulmonary dz - no tx
disseminated dz - amphotericin
Acute resp illness that causes joint pain and erythema nodosum - dry areas like Arizona
Acute pulm dz that may have bone lesions; Broad budding yeast from the rural southeast
amphotericin or itraconazole
how can you identify traumatic LP?
RBC > 6000/mm3 without xanthochromia
elevated WBC - 1:750-1000 RBCs
CSF WBC:RBC ratio < 0.01
100% negative predictive value for meningitis`
treatment of pregnant woman with chlamydia
erythromycin base 500 mg QID for 7d
amoxicillin 500 mg PO TID for 7d
chemoprophylaxis of meningococcal meningitis
1. Rifampin 600 mg PO bid for 4 doses
2. Ciprofloxacin 500 mg PO single dose
Which drug(s) does Rifampin interfere with?
steroids ex. OCP (decreases levels) - use an alternative
post-exposure prophylaxis of health care workers exposed to contagious patient with TB
1. immediate placement of PPD
- baseline immunologic status
2. repeat PPD test after three months
- check for any changes due to recent exposure
progressive ascending paralysis that occurs over matter of hours/days; fever and pupillary abnormalities are uncommon
management: tick paralysis
removal of tick - substantial improvement in paresis w/in hours
lesions of skin/mucous membranes that rapidly worsen and evolve into nodular patches marked by hemorrhage, ulceration and necrosis; caused by pseudomonas invasion of media and adventitia of arteries and veins followed by ischemic necrosis
Tx. pseudomonas bacteremia
1. aminoglycoside (tobramycin, amikacin) + piperacillin
2. antipseudomonal cephalosporin (ceftazidime, cefipime)
tx. herpes zoster
oral acyclovir, 800 mg 5x/day
steroids may help accelerate healing time but should not be used in patients with other comorbidities (diabeter, osteoporosis, HTN, glaucoma)
do patients with herpes zoster need to be placed in isolation?
if immunocompetent with localized case - no!
contact precautions recommended for hospitalized patients, pts with disseminated zoster or immunocompromised pts
tx. postherpetic neuralgia
TCAs (desimipramine, amitriptyline)
long acting oxycodone